Electric switch



F. R. QUINN ELECTRIC SWITCH Sept. 22, 1959 2 Sheets-Sheet 1 Filed July8, 1957 n n mm w HR 5 s. n F .l n

United States Patent ELECTRIC SWITCH} Frederic R. Quinn, Red Hook, N3.

Application July 8,1957, Serial No. 670,435

7- Claims: (or. 200-8 7) invention relates to electric switches, andmore especially torelay-operated toggle typeswitches and. other snapaction switches operating. ona. similar principle, and-has foritsprincipal object a substantial reduction in the weight and volume ofthe device for a given switching duty, or alternatively, asubstantialincrease inswitching capability for a given weight and volume. Otherobjects are increased life and reliability of the switch, and stillothers will be apparent from the following description and explanations.Although the invention was developed. for air-borne equipment, itsdesirability in other fields also will be evident.

The basic duty of an electric switch is to close and: to open anelectriccircuit, the latter duty being ingeneral the more difficult one. In anair-break: switch, the device performs this circuit opening; duty bybreaking the electrical continuity of the circuit by physicallyseparating two terminals of the circuit sufficiently far apart tointroduce an air-gap capable of withstanding the circuit voltage withoutbreak down. As'metallic contact is broken, an are or spark generallyfollows the break and tends to bridge the air-gap that is forming. Insuccessful switch. operation, this are or spark is extinguished verypromptly by the air gap. Failing this, the parting contacts are burntand damaged.

As alternating current passes through zero twice each cycle; thesezero-current instants'afford favorable movements for the extinguishingof the are or spark. However, this. causes the full circuit voltage toappear across the developing gap, tending to; restrike the are or,spark; It

will be. appreciated then that the speed with which the developing gapreaches its full design length may have a great deal to do with the:success or failure of opening the circuit.

Toggle type and. allied. snap switches are favored in small applicationsbecause they are: relatively simple, their contacts are stable and underpressurein their continuously operative positions, and can not. stay inan 'inbetwe'en position'partially open, partially closed. Al-

though theoretically there is a neutral in-between': positionat'whichthere is no force accelerating: the movable contact to one or to theother end position, yet this neut'ral position is highly unstable like apencil, balanced on its point, and the movable contact generally movesinto one or the other stable end position by the momentum acquired'whileapproaching that neutral position.

It may be appreciated on reflection that: the desirable characteristicsof a toggle switch are obtained. at a considerable price, seeing that,in the neighborhood of that neut'ral point, the movable contact is notaccelerated and gains no speed to shorten the opening time.

It is an object of the present invention therefore: to provide auxiliarymeans to furnish a substantial positive force to accelerate the movablecontact in the neighborhood of the neutral position characteristic ofatoggle type switch, and a preferred construction for this purpo'se'will now" be described.

2,905,785 Patented Sept. 22, 1959 e CC For an understanding of theinvention principles, referenceis made to the following description andthe accompanying drawings in which:

Fig; l is a magnified perspective view of a preferred embodying of theinvention in a small unit, with the cover plate of one side removed. toexpose to viewthe mechanism inside;

Fig. 2 is a cross-sectional view taken on the line 2-2 of Fig. 1;

Figs. 3 and 4 are plan views of the two members of the toggle mechanism;

Figs. 5, 6 and 7 are sectional elevation views illustrat; ing threeimportant operating positions of the toggle mechanism and other parts ofthe switch; and

Fig. 8 isa horizontal sectional view illustrating the construction anddisposition of the shading coil.

Referring now to Figures 1 and 2 together, 10 is a relay coil thatinitiates the operation of the switch; and 11a, 11b and 11c are thethree legs of a three-legged laminated elcctromagnet core around themiddle leg of which the relay coil is positioned. Part 12 is the movablearmature of the electromagnet and is hinged on legllc of the core, beingheld there by means of spring 12a, while 13 is a fixed magneticextension of leg 11a and overlaps the free end of armature 12 over themiddle leg of the core. Part 15 is a magnetic extension of leg to assistin conveying the magnetic flux of this leg toarmature 12 and also toprovide a pivoting groove for armature 12. A movable pin 14 runs throughan axial hole in the middle leg of the core, projecting both above andbelow the core, so that when the relay coil 10 is energized, magnetizingthe core, the armature 12 is pulled down over the middle leg and pressesdown on this pin. Below the core, this pin projects into a chamberformed by container 16 and there rests on a strip spring 17 which isshaped as shown and pivoted at its end 17a in a recess formed by the end18a of a fixed conductive strip 18 set at the bottom of the chamber and,made fast to a supporting and insulating foundation layer 18d by meansof a. rivet or screw 18c. The other end, 18b, of the strip 18 is shapedas shown so as to engage the portions 20a and 20b of element 20 which isone of the two toggle members. A plan of this member is to be seen inFigure 3. Part 21 is the other member of the toggle mechanism, shown inplan view in Figure 4. Portion 17b of the strip spring 17 is recessed toengage portion 21c (Fig. 4) of this toggle member. The two loops 21a and21b (Fig. 4) of the toggle member 21 engage. the portions 20:: and 20(Fig. 3) respectively of the toggle member 20 to form a toggle joint.

Part 22 is the fixed terminal of a circuit having the external lead 22a,and 23 is the fixed terminal of another circuit havingthe external lead23a, both to be controlled by the switch; and it will be seen thatportion 200 of part 20 (Fig. 1) is adapted to make contact with'eitherterminal 22 or 23 to close their respective circuits. Current flowinginto 20c from either 22 or 23 isconducted to 18b (Fig. l) and thence to18c (Fig. 2.) as. the common return circuit for the leads 22a and 23a.

The operation of the switch is as follows. Whenthe relay coil is notenergized, or weakly energized. below a. predetermined value, the.movable terminal 200 rests against terminal 23 (Figs. 1, 2 and 5), andtherefore the circuit of 23 is closed, and that of 22 is open. If therelay coil is energized above that predetermined value, the core becomessutficiently magnetized to pull down. the armature 12 with sufiicientpressure on pin 14' to depress the spring 17 downward, as. seen in.Figures. 6 and, 7.

In Figure 5, part 21 diverges. upwardly from: part- 20; in Figure 7,part 21 extends downwardly beyond part 20; andin Figure 6, the two parts(20. and 21). are substantially parallel and coplanar. The set of thespring 17 is such that, in the position shown in Figure 5, part 17b ispushing part 210 to the right. As this force has a downward componentwith respect to part 20, part 23 is pushed downward by loops 21a and 21b(Figs. 4, 5), and end 200 is held in contact with contact 23 under somepressure.

When spring 17 is depressed (Fig. 6), this component of force acting tothe right is diminished; and when parts 20 and 21 are in parallelism,loops 21a and 21b exert no force on part 20 upwards or downwards. Theaxial forces on parts 21 and 26 are actually greater in Figure 6 than inFigure 5, but they have no transverse com ponent to rotate parts 2% or21 at either pivot line 17b or 18b. This is the theoretical unstableneutral equilibrium position alluded to above. As spring 17 is depressedlower, and part 21 points below part 25} (Fig. 7), the large axial forceexerted by part 21 on part 20 acquires an upward component, raising thetoggle joint and toggle members upward, thus bring end 200 into contactwith contact 22 under some pressure.

The structure and operation of the switch described so far are those ofits toggle type structure, and now the additional and particularly novelfeatures will be described.

Part 20 has an extension 20d (Fig. 3) shown in Figures 1 and 5 as inclose proximity to portion 17d of the spring 17 but not under pressurefrom it. However, when spring 17 is depressed by pin 14 (Fig. 6),simultaneously with the changed action of spring part 17b on 21, andthrough it on member 20, an action is started also by spring portion 17don member extension 20d, presssing extension 20d downward and, bearingagainst portion 18b as a fulcrum, pushing the right hand portion of 20(and hence member 280) upward. In Fig. 6, part 17b develops only anaxial force on members 21 and 20, with no transverse component; but part17d does, and this force is not only a component force but the fulltotal force exerted by part 17d. Additionally, as the movement of member20 and its portion 200 under this force is rotational in nature, portion20c moves upward faster than portion Ztld moves downward in the ratio ofthe lever arms (2tlc20b) :(20b2ld). Thus, when breaking contact betweenportion 200 and contact 23, in the neighborhood of the position of end200 shown in Fig ure 6, the total accelerating force is not zero or verysmall but very substantial on account of the direct switching forceexerted by spring end 17d, and the moving contact 200 is acceleratedwith an increased force over a larger percentage of its travel. When endcontact 200 arrives at 22, the new electrical contact is held under thejoint pressure from spring parts 17d and 17b.

When switching back from the circuit of 22 to that of 23, the relaxationof pressure from pin 14 on spring 17 reduces both forces simultaneously,and as part 17 moves upward, end 210 also moves upward, and soon part 21develops suflicient downward component of force to carry the mechanisminto the position shown in Figure 5.

It may be observed that the supplemental force exerted by spring end 17dis particularly beneficial in breaking the contact at 23; and thereforein all those cases in which the current interrupting duty demanded bythe circuits of contact 22 and 23 are unequalwhich is frequently thecasethe circuit demanding the higher duty should be connected toterminal 23.

It may be pointed out also that, during the position of parallelismbetween members 20 and 21 (Fig. 6), the movable contact 200 need not behalf way between 22 and 23, but may be designed closer to one than theother depending on the relative switching duties involved.

Two further structural features of the invention that improve itsperformance are associated with the relay portion of the device andimprove the operating force developed by the armature 12.

To consider the first, at any given moment when the relay coil isenergized, the magnetic flux developed in the core may be thought of asflowing up in the two outside legs, 11a and 110, of the core (Fig. 2),then through part 13 and armature 12 respectively towards the middleleg, and then down through the middle leg. Thus the two outside legs ofthe core are of one polarity and the middle leg of opposite polarity. Tofurther clarify this important matter, it may be pointed out that parts12 and 13 cannot act as magnetic return to each other because both areof the same polarity. This then leads to the conclusion that there mustbe repulsion between the two as like poles, and as armature 12 is pulleddown from below by the middle leg 11b, it will be pushed down from aboveby the magnetic pole 13. As the initial gap between armature 12 and pole13 is negligible, and the final gap between armature 12 and leg 11b isnegligible, it follows that the force of repulsion starts with itsmaximum value, and as it gets weaker with increasing upper gap, the pullfrom below increases with the diminishing lower gap; and thus, armature12 is accelerated downward and held there with a more uniform resultantforce than by either component force.

The second feature of novelty associated with the relay portion of thedevice and improving its performance is the structure of theshort-circuited coil 10a (Figs. 2 and 8), generally called a shadingcoil, surrounding the middle leg of a group of the laminations. Thefunction of a shading coil is ordinarily spoken of as prevention ofchatter caused by the alternations of the magnetic flux, and it isconstructed as a single short-circuited turn around a portion of a poleface. Current in this short circuit is limited by the high reactance ofthe turn.

Contrasted with the foregoing theory and structure of shading coils, thefunction here aimed at is the development of a two-phase flux so as toexert on the armature a steady force more akin to that produced bydirect current. It is further recognized here that twophase flux willnot be produced if the current in the shading coil is limited byreactance, making it a zero or near-zero lagging power factor current:the shading coil current must be of high power factor to develop aquadrature phase flux in the portion of the core which it surrounds.This is accomplished in the present invention by making the shading coila long thin cylinder enclosing the full length of the core leg which itsurrounds; thin, to secure the desired high resistance; and long fullcoverage, to secure the desired low reactance.

Although the most extensive use of the present switch is likely to be incombination with a relay, as illustrated and described above, yet it isnot limited to such use, as it can be used also in combination with anyother device that can exert pressure on pin or button 14 in response toa predetermined situation, such as temperature responsive bimetallicstrips, pressure responsive bellows and other pneumatic and hydraulicdevices, and the multitude of other well-known control devices andtransducers.

The invention having been explained fully, clearly and concisely withthe help of an embodiment thereof that is now preferred as particularlysuitable for small units, various modifications thereof can be madewithout departure from the spirit of the invention and the scope of theappended claims.

I claim:

1. The switching device comprising in combination a toggle mechanismadapted to open and close an electric circuit, said toggle mechanismhaving two operating positions and a neutral position between said twooperating positions at which said mechanism is free from an accelcratingforce towards either one of said operating positions; a relay deviceadapted to actuate said toggle mechanism; and auxiliary linkage betweensaid relay device and said toggle mechanism and adapted to exert anaccelerating force on said toggle mechanism towards one of saidoperating positions when said toggle mechanism is in the neighborhood ofsaid neutral position; said relay device having a magnetic core with awinding leg, a relay coil surrounding said leg, a magnetic armaturemember movably positioned to be subject to attraction from said leg andadapted to actuate said toggle mechanism, said core comprising aplurality of magnetic laminations in parallel, and a low-reactanceclosed electrical circuit surrounding said winding leg of a fractionalgroup of said laminations for substantially the full length of saidwinding leg; said core being three-legged and comprising a stack of twogroups of E-shaped magnetic laminations, said relay coil surrounding themiddle leg of said stack, said closed circuit surrounding the middle legof one of said two groups of laminations, one end of said armature beinghinged and resting over one end leg of said core, the other and free endof said armature facing said middle leg of said core and subject toattraction by said middle leg, the other end leg of said core having anextension that reaches and overlaps said free end of said armature torepel said free end towards said middle leg when said core ismagnetized.

2. The switching device of claim 1, said winding leg having an axialhole, and a movable pin in said hole, said pin projecting beyond saidcore at each end and subject to axial pressure at one end from saidmovable armature when said armature is attracted by said winding leg,said pin being adapted to exert pressure at its other end on said togglemechanism to operate said mechanism.

3. The switching device of claim 2, said pin exerting pressure on saidmechanism through two linkages, one of said linkages transmitting tosaid toggle members a predominantly axial force, and said second linkagetransmitting to said toggle members a predominantly transverseaccelerating force.

4. A toggle switch mechanism comprising, in combination, a firstrelatively elongated contact member having a circuit controlling endnormally engaged with a first contact; a second relatively elongatedmember pivotally connected at one end to said first member intermediatethe ends of the latter and normally diverging from said first member; afirst spring element engaged with said first member; and a second springelement having an end engaged with said first element and a movable endengaged with the free end of said second member; said spring elementsbiasing said members in opposed longitudinal directions with said secondmember exerting a force on said first member in a downward direction;the movable end of said second element being movable downwardly to movethe free end of said second member downwardly below said first member tosnap the circuit controlling end of said first member upwardly to engagea second contact; and operating means engaged with said second springelement selectively operable to move its movable end downwardly.

5. A toggle switch mechanism comprising, in combination, a firstrelatively elongated contact member having a circuit controlling endnormally engaged with a first contact; a second relatively elongatedmember pivotally connected at one end to said first member intermediatethe ends of the latter and normally diverging from said first member; afirst spring element engaged with said first member; and a second springelement having an end engaged with said first element and a movable endengaged with the free end of said second member; said spring elementsbiasing said members in opposed longitudinal directions with said secondmember exerting a force on said first member in a downward direction;the movable end of said second element being movable downwardly to movethe free end of said second member downwardly below said first member tosnap the circuit controlling end of said first member upwardly to engagea second contact; and operating means engaged with said second springelement selectively operable to move its movable end downwardly; saidsecond element having a portion bearing against the opposite end of saidfirst member during downward movement of said movable end and movingsaid opposite end downwardly to augment the upward movement of saidcircuit controlling end.

6. A toggle switch mechanism as claimed in claim 4, in which said firstmember is a wire loop having transverse portions intermediate its endspivotally connected to said second member.

7. A toggle switch mechanism as claimed in claim 6 in which said secondmember is a U-shape wire having loops at its ends embracing saidtransverse portions.

References Cited in the file of this patent UNITED STATES PATENTS1,292,650 Rippl Jan. 28, 1919 1,485,750 Wolfe et al. Mar. 4, 19242,444,352 Hoffman June 29, 1948 2,486,061 Ransome Oct. 25, 19492,702,841 Bernstein Feb. 22, 1955 2,728,826 Lauder Dec. 27, 19552,743,331 Lauder Apr. 24, 1956 2,782,278 Peters Feb. 19, 1957 2,800,546Reitler July 23, 1957 2,821,587 Cherry, Jr. Jan. 28, 1958 2,825,013Krenke Feb. 25, 1958

